Chapter 3 Test Bank Questions with Verified Solutions
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Terms in this set (66)
The chirality of an amino acid The chirality of an amino acid results from the fact that its alpha
results from the fact that its carbon:
alpha carbon:
C) is bonded to four different chemical groups.
A) has no net charge.
B) is a carboxylic acid.
C) is bonded to four different
chemical groups.
D) is in the l absolute
configuration in naturally
occurring proteins.
E) is symmetric.
Of the 20 standard amino acids, Of the 20 standard amino acids, only ___________ is not optically
only ___________ is not optically active. The reason is that its side chain ___________.
active. The reason is that its side
chain ___________. B) glycine; is a hydrogen atom
A) alanine; is a simple methyl
group
B) glycine; is a hydrogen atom
C) glycine; is unbranched
D) lysine; contains only nitrogen
E) proline; forms a covalent
bond with the amino group
,Two amino acids of the standard Two amino acids of the standard 20 contain sulfur atoms. They
20 contain sulfur atoms. They are:
are:
C) methionine and cysteine
A) cysteine and serine.
B) cysteine and threonine.
C) methionine and cysteine
D) methionine and serine
E) threonine and serine.
All of the amino acids that are All of the amino acids that are found in proteins, except for
found in proteins, except for proline, contain a(n):
proline, contain a(n):
A) amino group.
A) amino group.
B) carbonyl group.
C) carboxyl group.
D) ester group.
E) thiol group.
Which of the following The following statement about aromatic amino acids is correct:
statements about aromatic
amino acids is correct? C) On a molar basis, tryptophan absorbs more ultraviolet light
than tyrosine.
A) All are strongly hydrophilic.
B) Histidine's ring structure
results in its being categorized
as aromatic or basic, depending
on pH.
C) On a molar basis, tryptophan
absorbs more ultraviolet light
than tyrosine.
D) The major contribution to the
characteristic absorption of
light at 280 nm by proteins is the
phenylalanine R group.
E) The presence of a ring
structure in its R group
determines whether or not an
amino acid is aromatic.
, Which of the following The following statement is correct:
statements about cystine is
correct? A) Cystine forms when the —CH2—SH R group is oxidized to
form a —CH2—S—S—CH2— disulfide bridge between two
A) Cystine forms when the — cysteines.
CH2—SH R group is oxidized to
form a —CH2—S—S—CH2—
disulfide bridge between two
cysteines.
B) Cystine is an example of a
nonstandard amino acid,
derived by linking two standard
amino acids.
C) Cystine is formed by the
oxidation of the carboxylic acid
group on cysteine.
D) Cystine is formed through a
peptide linkage between two
cysteines.
E) Two cystines are released
when a —CH2—S—S—CH2—
disulfide bridge is reduced to —
CH2—SH.
Amino acids are ampholytes Amino acids are ampholytes because they can function as either
because they can function as a(n):
either a(n):
A) acid or a base.
A) acid or a base.
B) neutral molecule or an ion.
C) polar or a nonpolar
molecule.
D) standard or a nonstandard
monomer in proteins.
E) transparent or a light-
absorbing compound.
Save
Terms in this set (66)
The chirality of an amino acid The chirality of an amino acid results from the fact that its alpha
results from the fact that its carbon:
alpha carbon:
C) is bonded to four different chemical groups.
A) has no net charge.
B) is a carboxylic acid.
C) is bonded to four different
chemical groups.
D) is in the l absolute
configuration in naturally
occurring proteins.
E) is symmetric.
Of the 20 standard amino acids, Of the 20 standard amino acids, only ___________ is not optically
only ___________ is not optically active. The reason is that its side chain ___________.
active. The reason is that its side
chain ___________. B) glycine; is a hydrogen atom
A) alanine; is a simple methyl
group
B) glycine; is a hydrogen atom
C) glycine; is unbranched
D) lysine; contains only nitrogen
E) proline; forms a covalent
bond with the amino group
,Two amino acids of the standard Two amino acids of the standard 20 contain sulfur atoms. They
20 contain sulfur atoms. They are:
are:
C) methionine and cysteine
A) cysteine and serine.
B) cysteine and threonine.
C) methionine and cysteine
D) methionine and serine
E) threonine and serine.
All of the amino acids that are All of the amino acids that are found in proteins, except for
found in proteins, except for proline, contain a(n):
proline, contain a(n):
A) amino group.
A) amino group.
B) carbonyl group.
C) carboxyl group.
D) ester group.
E) thiol group.
Which of the following The following statement about aromatic amino acids is correct:
statements about aromatic
amino acids is correct? C) On a molar basis, tryptophan absorbs more ultraviolet light
than tyrosine.
A) All are strongly hydrophilic.
B) Histidine's ring structure
results in its being categorized
as aromatic or basic, depending
on pH.
C) On a molar basis, tryptophan
absorbs more ultraviolet light
than tyrosine.
D) The major contribution to the
characteristic absorption of
light at 280 nm by proteins is the
phenylalanine R group.
E) The presence of a ring
structure in its R group
determines whether or not an
amino acid is aromatic.
, Which of the following The following statement is correct:
statements about cystine is
correct? A) Cystine forms when the —CH2—SH R group is oxidized to
form a —CH2—S—S—CH2— disulfide bridge between two
A) Cystine forms when the — cysteines.
CH2—SH R group is oxidized to
form a —CH2—S—S—CH2—
disulfide bridge between two
cysteines.
B) Cystine is an example of a
nonstandard amino acid,
derived by linking two standard
amino acids.
C) Cystine is formed by the
oxidation of the carboxylic acid
group on cysteine.
D) Cystine is formed through a
peptide linkage between two
cysteines.
E) Two cystines are released
when a —CH2—S—S—CH2—
disulfide bridge is reduced to —
CH2—SH.
Amino acids are ampholytes Amino acids are ampholytes because they can function as either
because they can function as a(n):
either a(n):
A) acid or a base.
A) acid or a base.
B) neutral molecule or an ion.
C) polar or a nonpolar
molecule.
D) standard or a nonstandard
monomer in proteins.
E) transparent or a light-
absorbing compound.
